This invention relates to the use of solar energy as a power source. More specifically, this invention relates to a turbine system having a turbine rotatably driven by solar-heated air for driving rotational machinery such as electrical generators or the like.
Considerable emphasis recently has been focused upon the use of solar energy as a source of motive power. In this regard, a wide variety of devices have been proposed for converting heat energy obtained from solar radiation into usable power such as electrical power or the like. Developments in this area have included solar-powered photocells which chemically convert solar radiation into usable electrical energy. These systems are, of course, highly desirable in that solar radiation is freely available, thereby reducing or eliminating the demand for conventional and less readily available fossil-type fuels.
Recent developments in the solar energy area have included proposals for utilizing solar energy for driving rotational equipment such as turbines or the like. In this regard, turbine-driven generators are quite attractive for use in the conversion of solar energy because of the relatively high efficiency of turbomachinery rotating groups, and because of the relatively long operating life of such equipment. In the prior art, turbine-driven generator sets have been proposed wherein solar energy is concentrated and focused upon an absorber as by means of a solar heliostat. The solar absorber has typically comprised a device for transferring the concentrated solar radiation energy to a high temperature, high pressure working fluid as by means of a relatively complex heat exchanger. The high pressure working fluid in turn is expanded through a high pressure turbine for conversion to rotational energy for driving electrical generators or the like. See, for example, U.S. Pat. No. 4,033,118 for an example of this type of system. However, these systems have not been widely used because of the complexity and expense of the heat exchanger, together with the required relatively large sizes of the heat exchanger and the radiation-collecting heliostat.
Some solar-powered systems have been proposed which attempt to eliminate the high pressure, high temperature heat exchanger used as a solar absorber. See, for example, U.S. Pat. No. 3,203,167 which discloses an atmospheric pressure solar absorber for transferring heat energy to ambient air which is then injected into a high pressure turbo-compressor cycle by means of a supersonic jet pump. However, the requirement of the jet pump, together with the high pressures and temperatures required for operating the turbo-compressor rotating group, still results in a relatively expensive and complex system which has not been commercially accepted.
The invention of this application provides an improved solar-powered turbine system which eliminates expensive and complicated heat transfer apparatus, and which is capable of operating at relatively low temperatures and pressures.